<template>
  <div class='xtx-carousel' @mouseenter="stop()" @mouseleave="start()">
  <!--轮播图片容器-->
    <ul class="carousel-body">
    <!--dade显示的图片加上-->
      <li class="carousel-item" v-for="(item,i) in sliders" :key="i" :class="{fade:index===i}">
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="">
        </RouterLink>
      </li>
    </ul>
    <!--上一张 -->
    <a @click="toggle(-1)" href="javascript:;" class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <!--下一张 -->
    <a @click="toggle(+1)" href="javascript:;" class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <!--指示器 -->
    <div class="carousel-indicator">
    <!--active 激活点-->
      <span @click="index=i" v-for="(item,i) in sliders" :key="i" :class="{active:index===i}"></span>
    </div>
  </div>
</template>

<script>
import {onUnmounted, ref,watch} from 'vue'
export default {
  name: 'XtxCarousel',
  props:{
    //轮播图数据
    sliders:{
      type:Array,
      default:()=>[]
    },
    //是否自动轮播
    duration: {
      type: Number,
      default: 3000
    },
    autoPlay: {
      type: Boolean,
      default: false
    }
  },
  setup(props){
    // 控制显示图片的索引
    const index=ref(0)

    //自动轮播图的逻辑
      // 自动播放
    let timer = null
    const autoPlayFn = () => {
      //防止定时器重复
      clearInterval(timer)
      timer = setInterval(() => {
        index.value++
        if (index.value >= props.sliders.length) {
         index.value = 0
        }
      }, props.duration)    }
    watch(() => props.sliders, (newVal) => {
      // 有数据&开启自动播放，才调用自动播放函数
      if (newVal.length && props.autoPlay) {
        index.value = 0
        autoPlayFn()
      }
    }, { immediate: true })

    //2.鼠标进入暂停，离开开启自动播放（有开启条件）
    const stop = () => {
      if (timer) clearInterval(timer)
    }
    const start = () => {
      if (props.sliders.length && props.autoPlay) {
        autoPlayFn()
      }
    }
    const toggle=(step)=>{
      //将要改变的索引
        const newIndex=index.value+step
        //超出的情况 太大了
        if(newIndex>(props.sliders.length-1)){
          index.value=0
          return
        }
        //超出的情况太小了
        if(newIndex<0){
          index.value=props.sliders.length-1
          return
        }
        //正常
        index.value=newIndex
    }
    //4.组件卸载，清除定时器
    onUnmounted(()=>{
      clearInterval(timer)
    })
    return { index, stop, start,toggle }
    //3.点击点可以切换
  }
}
</script>
<style scoped lang="less">
.xtx-carousel{
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel{
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0,0,0,0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background:  #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0,0,0,.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev{
        left: 20px;
      }
      &.next{
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>